Gas extraction is a major measure for solving a gas gush problem and preventing gas outburst in the mining process of a coal seam with high gas concentration and low air permeability. However, owing to the low air permeability of coal seams with high gas concentration and low air permeability, it is difficult to carry out gas extraction in the conventional way and the gas extraction effect is poor; hence, technical measures for pressure relief and permeability improvement are required. Coal seam fracturing and permeability improvement techniques are important means to solve the ubiquitous problems of micro-porosity, low permeability and high absorptivity in coal seams with a high gas outburst risk in China. Domestic and foreign researchers have made extensive researches on pressure relief and permeability improvement techniques for coal seams, and have obtained some results. Existing effective pressure relief and permeability improvement techniques mainly include: intensive borehole drilling, high pressure water jet slotting, deep-hole loose blasting, and hydraulic fracturing, etc. However, most of the existing techniques have drawbacks such as complex process, high construction workload, high cost, and limited range of application, etc.